Conceptual Design of Mixed- spectrum Supercritical Water Reactor T. K. Kim T. K. Kim Argonne National Laboratory

1 Challenges of SCWR design in Neutronics Axial power shape controlAxial power shape control –Large coolant density variation axially –Smaller control rod worth Radioactive waste controlRadioactive waste control –Fast spectrum of SCWR can burn higher actinides Neutronics code systemNeutronics code system –Multi-group, 3 dimensional, T/H coupling system –HTC correlation in supercritical conditions Other issuesOther issues –Proliferation resistance and economy

2 Argonne National Laboratory Mixed Spectrum SCWR Concept Advanced spectrum control is needed to maximize merits of SCWRAdvanced spectrum control is needed to maximize merits of SCWR Mixed-spectrum supercritical water reactorMixed-spectrum supercritical water reactor –Separation fast and thermal spectrum radially Smaller power peaking factor and easier reactivity controlSmaller power peaking factor and easier reactivity control –Multi-purposed reactor Maximize thermal efficiency and economy of SCWR concept without additional design featuresMaximize thermal efficiency and economy of SCWR concept without additional design features Electric production and actinide Burning in fast spectral coreElectric production and actinide Burning in fast spectral core

3 Argonne National Laboratory MS 2 core

4 Argonne National Laboratory Comparison of SCWR Assemblies MS 2 assembly SCLWR-H and INEEL SCLWR-H old

5 Argonne National Laboratory Comparison of SCWR Designs SCLWR-H 1) SCFR-H 1) INEEL 2) MS 2 PWR Inner core Outer core Thermal power, MW Number of fuel assembly Active height, cm Power density, MW/m 3 Fuel material Cladding material Fuel radius, cm Cladding thickness, cm Fuel pitch, cm P/D of fuel cell Assembly Shape Number of fuel rods Assembly pitch, cm UO 2 Ni-Alloy hexagonal MOXNi-Alloy hexagonal ODS steel square MOXNi-Alloy hexagonal MOXNi-Alloy hexagonal hexagonal UO 2 Zr square Inlet temperature (in/out), o C 280/508280/526280/500387/553280/387300/332 Coolant mass flow rate, kg/s Coolant velocity (in/out),m/sec 2.5 / / / / / / / / / / / High Temperature Supercritical thermal reactor (O. Oka, "Design Concept of Once-Through Cycle Supercritical-Pressure Light Water Reactors," SCR-2000, Tokyo (2000) 2. INEEL design (tentative)

6 Argonne National Laboratory WIMS8/SOLTRAN Code System WIMS8 used for lattice calculationsWIMS8 used for lattice calculations Zonal cross sections are functionalized by state parameters,Zonal cross sections are functionalized by state parameters, SOLTRAN used for core calculationsSOLTRAN used for core calculations –Interface current nodal formulation of diffusion and simplified P 2 equation in multi-dimensional hex-Z and X-Y-Z geometry –Multi-group, microscopic depletion –Single-phase heat balance equation for T/H feedback –HTC is updated by DB-, Modified DB-, and Jackson’s correlations

7 Argonne National Laboratory MS 2 Core Analysis (1) BurnerBurner –Inner core : MOX Th/TRU/U = 32.5/15/32.5 %Th/TRU/U = 32.5/15/32.5 % Fissile fraction = 11%Fissile fraction = 11% –Outer core : MOX Th/Pu/U = 3/8/89 %Th/Pu/U = 3/8/89 % Fissile fraction = 6.5%Fissile fraction = 6.5% ConverterConverter –Inner core : MOX Th/Pu/U = 3/8/89 %Th/Pu/U = 3/8/89 % Fissile fraction = 6.5%Fissile fraction = 6.5% –Outer core : MOX Th/Pu/U = 3/8/89 %Th/Pu/U = 3/8/89 % Fissile fraction = 6.5%Fissile fraction = 6.5%

8 Argonne National Laboratory MS 2 Core Analysis (2) HTC = Jackson ’ s correlation

9 Argonne National Laboratory Comparison of Axial Power and Temperature Axial power distribution Axial cladding surface temperature distribution Axial coolant temperature distribution

10 Argonne National Laboratory Comparison of MS 2 Cores BurnerBurner –Heterogeneous core (higher TRU and fissile content in inner core) –40/60 % power sharing in inner/outer cores –Higher power peaking factor in inner core due to higher fissile content –Cladding temperature of outer core is much lower than criteria due to lower power peaking factor ConverterConverter –Homogeneous core (same fuel composition of inner and outer cores) –25/75 % power sharing in inner/outer cores due to coolant density difference –Higher power peaking factor in outer core, which causes higher cladding surface temperature

11 Argonne National Laboratory Conclusions and Future Works Conceptual design of MS 2 core was performedConceptual design of MS 2 core was performed –WIMS/SOLTRAN code system was developed for supercritical water reactor core analysis –Feasibility of burner and converter with mixed-spectrum SCWR was evaluated, but design optimizations are necessary Future worksFuture works –Optimize the core design for burner and converter –Fuel cycle analysis –Evaluation of waste and economics